AW: Bioaccumulation of 137Cs in fish

[Franz, Schoenhofer]

-----Ursprüngliche Nachricht-----

Von: owner-radsafe@list.vanderbilt.edu

[mailto:owner-radsafe@list.vanderbilt.edu]Im Auftrag von Michael

McNaughton

Gesendet: Dienstag, 08. Juli 2003 18:22

An: Radsafepost

Betreff: Bioaccumulation of 137Cs in fish





Dear Radsafers



The RESRAD code uses a bioaccumulation factor of 2000 for 137Cs in

freshwater fish. This seems to derive from NCRP Report No. 76 page 139. Is

this the latest and greatest info? What are your favorite values and

references for this bioaccumulation factor? To save bandwidth, if you reply

to me I will combine the results and report back to Radsafe with a summary.



-----------------------------



Dear Mike,



I do not follow your advice to save bandwidth, because I think that my reply

might be of interest for the RADSAFE community. Please forgive me....



I have since the Chernobyl accident fought the concept of a "bioaccumulation

factor of Cs-137 to freshwater fish". The reason is simple: Such a factor

does not exist! The accumulation factors depend on a large number of factors

which are associated with an even larger number of factors determined by the

environment.



I can provide some information from our experience after the Chernobyl

accident in Austria:



Not surprisingly the input of Cs-137 is the main factor. Depending on the

lake (or river) system the Cs-137 available for uptake will vary. The

species of fish is very important: The higher its rank in the food chain,

the higher was the Cs-137 contamination in fish-muscle. The conditions of

the various lakes and rivers according to their status played another big

role.



This is not only of academic interest. While in Austria no strict limit was

set as to the contamination of fish (fresh-water fish consumption is about

700 g per average Austrian) for instance in Finland, where no strict limits

for food were issued it was recommended, not to eat too much of young

perches, caught in small lakes, because they were known to accumulate high

concentrationsd of Cs-137 - so the difference in accumulation factors in

different species of fish and lakes, really played a role. This backs my

recommendation, not to use a single "transfer factor" for water-fish,

because

this is a very complex story.



Best regards,



Franz

















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